OBJECTIVES: The current study examines the awakening cortisol level in midlife mothers (M = 51.4 years old, SD = 8.4) of individuals (M = 22.1 years old, SD = 7.1) with autism spectrum disorders (ASD) under stressful conditions that are not specific to their son or daughter's ASD symptoms.METHODS: In addition to completing a set of questionnaires and in-home interviews, 82 mothers from the Adolescents and Adults with Autism Study (AAA) participated in a Daily Diary Study.RESULTS: Findings from the multilevel models indicated that mothers who previously were exposed to no negative life events in the previous period had an increased awakening cortisol level on days following a greater number and more severe stressors, a normative stress response. In contrast, we observed a flatter cortisol level of daily stressors in mothers who experienced a greater number of negative life events in the previous period.CONCLUSION: These findings highlight the sustained toll that global and everyday stressors have on awakening cortisol level of midlife and aging mothers of individuals with ASD.